The Hazelrigg Industries 4DI is a 4-channel vacuum tube direct box that combines a fully all-triode design with high-headroom circuits. It offers enhanced audio performance for electric bass, guitar, synthesizers, and acoustic instruments, all housed in a 2U rackmount enclosure.

Features and Design

The 4DI is based on the legendary D.W. Fearn VT-1/F, re-engineered to offer four channels instead of the original two, making it suitable for both stage and studio applications. Its all-triode vacuum tube design ensures exceptional sound quality, adding power, depth, and dynamic range to any instrument it connects to, from electric basses to synthesizers and acoustic guitars.

Front Panel Layout

The front panel has four locking ¼” instrument inputs, giving reliable connections for all inputs. Each channel also features a ground lift switch with LED indicators to signal ground lift status and signal presence. These controls allow for clear and stable performance in live or studio settings, reducing unwanted noise or hum.

Rear Panel Connections

On the rear panel, users find four additional ¼” input and passthrough jacks, wired in parallel with the front panel connectors. This setup allows easy integration into larger signal chains. Additionally, there are four XLR microphone-level outputs for each channel, providing flexibility for routing signals to mixing consoles or recording devices. The rear panel also includes an IEC mains socket, a power switch, and a voltage selector (115V-220V) for international compatibility.

Performance and Applications

With its high-headroom circuit design, the 4DI enhances the natural sound of electric and acoustic instruments. It delivers powerful, dynamic results for bass and guitar, adds warmth and richness to synthesizers, and brings realism to piezo-equipped acoustic instruments. This makes it an indispensable tool for professional audio environments where sound quality and reliability are paramount.